Acer has not officially released 2.2 for this phone HOWEVER there is an easy way to flash the Liquid E ROM onto the Liquid A1 and everything (all hardware) works well. Note that doing this does not root your device but does void your warranty (though if your device works and you need warranty repair, best way would be to re-flash Eclair AAP-GEN2. However, I do not think that there is still warranty for a phone this old, not entirely sure tho).

And that will get FroYo on your phone. Btw, on first boot, the phone will boot into Acer UI. Play around with it, see if you like it, and if you do not go into Settings-->Applications-->User Interface-->Android UI to switch back to standard Android UI.